Use regulated power supply for all sensors.
I have the OOPIC-R board. On this board they divided the I/O pins in groups of 5. Each group's power line goes to a jumper from which the user can select either 5v or unregulated. Why don't you do just that?
I use this board to control an arm with 6 servos, the pan and tilt head (2 servos), a PING ultrasonic sensor, an Eltec pyro sensor and an IR sensor for the gripper. I have grouped the devices like this: US sensor, Eltec sensor, IR sensor and the 2 servos for the head on the first group, powered with 5v. All the other servos (for the arm) are powered from the 6V battery (unregulated). So you see, you can have both ways with just a jumper.